Cylindrical paper stock screen



May 9, 1961 Filed March 17, 1958 H. G. CRAM CYLINDRICAL PAPER STOCK SCREEN 3 Sheets-Sheet 1 I ,3 m J HEk V E Y EPERAM ATTORNEYS y 1961 H. G. CRAM CYLINDRICAL PAPER s'rocx SCREEN 3 Sheets-Sheet 2 Filed March 17, 1958 m W R N G E Y v E mv R E H ATTORNEYS y 1961 H. G. CRAM 2,983,379

CYLINDRICAL PAPER STOCK SCREEN Filed March 17, 1958 3 Sheets-Sheet 3 INVENTOR HERVEY G. CRAM ATTORNEYS Unite S eer-Paw -Q PAPER STOCK 4 Hervey G. Cram, Appleton, Wis., assignor to Combined L'ocks Paper Company, Combined Locks, Wis., a corporation 1 Filed Mar. 17, 1958, Ser. No. 722,624 '1 Claims. (Cl. 209-273 This invention appertains to the art of paper making and more particularly to the screening 'of paper stock, pulp and the like. I

One of the primary objects of my invention-is to provide means for continuously screening paper stock by the use of anovel' cylindrical-screen constructed and ar- ,Patented May 9, 1961 i screening efiiciency with relation-to the screening section area..-

Anotherv further important. object of my invention is the novel arrangement of the. inlet of the stock relative to the spiral blade, whereby vtheinco'ming stock will impinge upon the blade-and thus, tend to turn the freely rotatable blade sorthat any power 'requir ed for rotating the blade will be reduced to a minimum.

ranged in such a manner that a compactand durable v.

structure will be had'and so that the screen itself will not be effected by wear incident to the passage of fibers therethrough. 1 v

It has been proposed to-utilize a cylindrical screen formed from a metal shell having a plurality of spaced perforations or slots of. a selected size therein. The con tinuous passage of-the stock with the suspended fibers therein soon causes wear on the walls of the openings or slots, resulting in the enlargement of the openings or slots. This necessitates the frequent changing of the screens with consequent cost and loss of time in the shutting down of the apparatus. I

- It is, therefore, another salient object of my invention to provide a cylindrical screen having a continuous spiral slot therein t erminating unobstructed at its discharge end; so that a continuous flow of acceptable stock therethrough from one end of the'scree'n to the-other is in'sured'with out-appreciable wear'thereon. e

A further object of my invention is to provide a'cylindrical screen formed from a continuously wound spiral band having a Width greater than its thickness with the convolutions of the band equidistantly spaced throughout the screen, the Width of the band insuring longevity of the screen incident to any Wear thereon." Y

A further important object of the inventionis to pit. vide an axially pivoted spiral blade disposed within a' screen having a continuous spiral slot to bring'about a required rotational minimum non-contact relation with the screen for insuring the correct flow of stock through the 'entire-le'ngthof' the screen and to cause thedesired blade being of such a construction as to cause a pulsa tion of stock through the screen and thus insure the proper cleaning thereof at all times, the blade also funetioning to'- assist in the movement of the rejected material toward the discharge end of the apparatus. 1

A still further object of the invention'is to provide means forthe control of the rotationabspeed of the' spiral blade so that the'time required for the passage of unscrcened stock to pass-from one end 'ofthe screen'to the other can be accurately governed according tothe quality of the stock, i.e., the amount-of acceptedstock passing through the screening section, and/ or, the amount of acceptable stock passing along with the rejected mate rial.

A still provide a hollow cylindrical body mounted within the cylindrical screen and carrying the spiral blade, whereby the interior area of the-screen will be materially reduced so as to provide a comparativelythin mass of unscreened stock in contact with the spiral screen and thus effect a With these and other objects in View, the invention consists in the novel construction, arrangement and formation of parts, as; will .be hereinafter more specifically described and claimed, and illustrated in the accompanying drawings,-in which drawings, 1

Figure 1 is..a longitudinalsectional view through my novel screening machine;

Figure .2 is a fragmentary transverse smtional view taken through the improved machine on the line 2-2 of Figure 1, looking in the direction of the arrows, the view flow of acceptable stock through the screen, the spiral I further important object of the invention is to I being ona greater scale than Figure 1; 1

Figure 3 is an enlarged fragmentary detail transverse sectional viewthrough the screen itself illustrating the manner of mountingthe spiral screen body on its sup porting bars; a a Figure 4 is a fragmentary longitudinal sectional view through the screen taken on the, line 4-4 of Figure 3, looking in the direction of the arrows, and Figure 5 is an enlarged fragmentary side elevational view of the screen body with its supporting bars removed to more clearly show the continuous spiral slot. 7 Referring to .the drawings in detail, wherein similar reference charactersvdesignate corresponding parts throughout the several'views, the letter M generally indicates the screening machine and the same includes a supporting frame 10 of any preferred character. The frame can include a base plate 11 having mounted thereon a frame body 12 to which is welded, or otherwise secured, transversely extending spaced bracket plates 13. At one end of the body 12 is fixed a supporting column 14 towhich is firmly secured the base of the drivemotor '15. The drive motor 15 is provided with a variable speed control 16 of a well known charactenj 'The purpose of the motor, 15 and its speed control 16 will later appear.

Extending longitudinally of the frame 10 is a cylindrical; casing 17 and .the same is firmly supported byathe bracket plates 13.- Welded to the outer surface of the cylindrical casin'g- 17 at its terminals "are fastening rings 18 and these rings areadapted to abut against the casing heads 19 and 20. Itis to'be noted that the inner faces of the casing heads 19 and 20 are shouldered, as .at 21, to receive and support the casing. Bolts 22 are utilized to fasten the securingrings 18 to the casing heads 19 and 20 and certain of these bolts can'be utilized to con nect the casing with the bracket plates 13.

I Secured 'to the casing head 19 is the hollow inlet head 23 for unscreened stock and secured to the casing head 20 is a hollow head 24 for rejected material. Communieating with the head 23 is a supply pipe 25 for unscreened stock-and this pipecan lead from any suitable source of supply. The head 24 hascommunicating there with a depending pipe 26-for rejected material. The casing 17, itself, carries an outlet pipe 27 for accepted stock. 1 a

The casing 17 has mounted axially therein the longitudinally extending screening section 28 which divides" the casing into an outer chamber 29 for accepted stock and an inner chamber 30 for unscreened stock. .The screening section 28 forms an important feature of this. invention and. it is to be noted that the same extends from one end of the casing to the other. 'The screening section 28 is provided with a spiral slot 31 which extends from one end of the screen to the other, and thus from] one end of the casing to the other. To form the cylindrical screen section 28 with its spiral slot, a relatively thin metal band 32is spirally wound and it is to be noted that the Width of the band is greater than its thickness. The band is firmly held by supporting bars 33 which extend longitudinally of the screen and these bars are equidistantly spaced around the periphery of the screen. The ends of the bars are received in notches 34 formed in the inner edges of annular plates 35 fitted Within the casing 17; The inner edges of the supporting bars 33 carry longitudinally extending rubber" or like resilient strips 36 and the spirally wound band '32 embeds itself in the resilient strips and these strips 36 eifectively hold v the convolutions of the band at their desired equidistantly spaced relationship throughout the entire length of the screen.

Rotatably mounted within the screening section 28 is the hollow dilution body 37. This body is in the nature of a cylinder and the same extends beyond the opposite ends of the screen. Firmly afiixed to the ends of the dilution body 37 are end collars 38 and 39. Secured to the collar 38 is a drive shaft 40 and this shaft is connected by a coupling 41 to the armature or output shaft 42 of the motor 15. The collar 39 has firmly secured thereto a pipe 43 for dilution water (White water). The shaft 40 and the pipe 43 are rotatably mounted in suitable supporting bearings 44 and 45 carried by the inlet head 23 and the dilution head 24. The pipe 43 leads to a slip joint 46 and this joint has connected therewith the pipe 4-7 for the dilution Water. Flow of the dilution water 47 into the dilution body 37 is controlled by a valve 48 disposed in the length of the pipe 47.

Carried by and rotatable with the dilution body 37 is a spiral blade 49 and the outer edge of the blade is disposed in close proximity to, but slightly spaced from, the inner surface of the screening section 28. The outer edge of this blade has its inner surface beveled, as at 50, for a purpose, which will now appear.

The dilution body 37 is of a definite size in relation to the interior diameter of the screen section 28' so that the interior area of the screening section will be materially reduced. This only permits a comparatively thin mass of unscreened stock to pass along the interior ofthe screening section 28 to bring about a maximum screening efliciency with relation to the screening section area.

' The dilution body 37, itself, is provided with a slot 51 so as to permit the flow of dilution Water from the dilution body into the unscreened stock chamber 30. The dilution water enters axially through the dilution body 37 and this dilution water is discharged into the unscreened stock at a required point for the effective separation of the acceptable stock and the rejected stock.

At this point, it is to be noted that the speed of rotation of the dilution body 37 and its spiral blade 49 is effectively controlled'by the speed of the motor 15. This is important, as obviously, the speed of rotation of the. spiral blade is governed according to the quality of the stock being supplied to the machine. It is also to be noted, that the travel of the unscreened stock along the.

Hence, the lead of the spiral.

As an example, of the passage of the stock through the machine, the following is given.

With the spiral blade 49 in a fixed stationary position, and, with a screening section diameter of 12 inches and a'length of twenty inches, and the spiral blade having a lead of three inches, the unscreened stock would travel: 24/3 3.1416, or approximately 25 feet in passing from end to end of the screen. However, in order to be efiective in clearing the screening section, i.e., continually moving the rejected material along the screening section for discharge at the end, it is essential that the spiral runner be in rotation, and, the speed of its rotation directly alfects:

(1) The time allowed forcontact with=the screening section in passing.

(2) The length (spiral) of screen contact in passing.

(3) The rate of flow through the screen.

(4) The direction angle of the unscreenedstock with the screening section slot in passing.

Therefore, based on a fixed pressure delivery to the screen, the cleanliness of the rejected material, or in other Words, freeness of acceptable material therein is directly relative to the rotational speed of the spiral runner blade, and, is the reason for the provision of the adjustable speed control requirement aspreviously mentioned.

While I have illustrated the invention as applied to a cylindrical'screen, it'isato be understood that theprinciples of my invention are equally applicable to flat or conical disc screens. In disc type screens the strip is spirally wound from the center to the periphery and the continuous slot is thus formed.

Changes in details may be made without departing from the spirit or the scope of this invention, but what I claim as new is: j 1

1. In a machine for screening paper stock and the like, a cylindrical casing having an inlet at oneend for unscreened stock and anoutlet at its other end for rejected stock, a stationary cylindrical screen in saidcasing dividing the casing into an interior chamber for-unscreened stock and an outer chamber ,,for acceptable stock, said inner chamber communicating at one end .with the inlet for unscreened stock and withthe outlet for rejected stock at its other end, said casing havingan outlet communicating with the outer chamber for. acceptable stock, and a longitudinally extending hollow dilution body disposed within said cylindrical screen and disposed axially thereof, means for supplying dilution water to the body, and said body having an outlet for dilution water intermediate its. ends.

2. Ina machinefor screening paper stock and the like as defined in claim 1,.and said dilution body. having a diameter less than the interior diameter of the cylindrical screen but in close relation thereto, wherebyunscreened stock will pass between the/dilution chamber" and the cylindrical screen in a thin mass.

3. In a machine for screening paper stock and the like as defined in claim 2, and means between the dilution-body andthe cylindrical screen for forcing the thin mass of material in a spiral path past the screen.

4. -In a machine for screening paper stockand the like aspdefined in claim 2, and a spiral blade carried by the outer surface of the dilution body terminating adjacent the inner surfacev of said cylindrical screen and spaced slightly therefrom. 5. In a machine for screeningpaper stock as defined in claim 3, means for rotatably supporting the, dilution body, and a spiral blade carried by the outer surface ofthe dilu-. tion body extending substantially from one end of the screen to the other. 1

6. In a machine for screening paper stock and the like as defined in claim 3, and said cylindricalscreen having a continuous spiral slot extending from one end thereof to the other, means rotatably supporting the ilution ody iut e cy i drical screen. andaspiral blade 5 1 carried by the outer surface of the dilution body extending substantially the full length of the screen.

7. In a machine for screening paper stock and the like as defined in claim 6, and said spiral blade having its outer edge beveled in the direction of the outlet for 5 rejected stock.

References Cited in the file of this patent UNITED STATES PATENTS 1,225,198 Westby May 8, 1917 6 Naugle Aug. 5, 1930 Heinrich Aug. 8, 1933 Infanger July 6, 1954 FOREIGN PATENTS Great Britain Jan. 12, 1875 Great Britain Sept. 16, 1902 Great Britain Apr. 14, 1923 Great Britain Dec. 13, 1926 France Dec. 3, 1956 

